#define _CRT_SECURE_NO_WARNINGS 1 
#include<stdio.h>

int main()
{
	int arr[] = { 1,2,3,4,5,6,7,8,9,10 };
	int n = 0;
	scanf("%d", &n);
	int left = 0;
	int right = sizeof(arr) / sizeof(arr[0])-1;
	int flag = 0;
	while (left<=right)
	{
		int mid = 0;
		mid = (left + right) / 2;
		if (arr[mid] < n)
		{
			left = mid + 1;
		}
		else if (arr[mid] > n)
		{
			right = mid-1;

		}
		else
		{
		
			printf("ҵˣ±Ϊ%d",mid);
			flag = 1;
			break;
		}
	}
	if (flag == 0)
		printf("Ҳ");
	return 0;
}